Speed control motor sensors

A starter or contactor with manual push-button or thermostatic operation to start and stop the fan normally controls simple systems. More complex systems that incorporate components that need control or monitoring are normally operated from purpose-built central control panels. The most common functions provided are fan motor stop, start and speed control, damper control, filter-condition indication and heater battery control. For optimum control, the system should be automatically controlled from thermostats or other sensors and a timeswitch. 

The control unit signals the motor to produce these speeds. The motor starts up slowly, then gradually increases speed. The speed sensor, a tachogenerator, keeps the control unit informed as to the speed that has been reached. The control unit uses the information to control the power to the motor and so controls the speed of the 10 drum at all times. 

If the product is being stripped from the carrier, the take-up system is a bit more complex. The speed control to provide constant speed during the cast is actually on the take-up roll for the carrier, and this speed is maintained by the tachometer feedback loop described previously The product, on the other hand, must be handled with a tensionless take-up system, since there is no carrier to provide the mechanical strength needed in a system under tension. This is accomplished by using a proximity sensor with a loop of tape where a servo-motor accelerates and decelerates the take-up roller, depending on where the loop is with respect to the sensor. This system provides a tensionless take-up system for the tape-cast product. Many different types of proximity sensors have been used in these systems. The main requirement is that the sensor detects the tape that is being speed controlled. At times, especially when the tape-cast product "blocks —that is, sticks to itself—a paper or other material must be interwoven between the layers on the roll. Machines have been built with all of these features added as options. 

Sensors TS 1-2-4 regulate the batteries for heating and cooling in a se quence to achieve the required temperatures (Fig. 9.56). Regulating valves for heat recovery are controlled by a frequency converter RCl for the pump motor. When a greater output is required from the heating battery, the pump motor speed increases before the valve MV2 opens. If the extract temperature is lower than the outdoor temperature, the speed of the pump motor increases before valve MVl opens. To avoid ice formation at low outdoor temperatures, the sensor TS7 operates on a lower limit, depending on the demands of the battery in the exhaust. 

However, motor speed was also the first function in washing machines to be electronically controlled. The standard nowadays are controllable AC- or DC-mo-tors. Depending on the textile type or wash program, such drives can be used to achieve optimal wash speeds, reversing rhythms and activation times. Usually a tachogenerator on the motor is used as a speed sensor. Such a smaller modem motor, connected to a small electronic control unit, is shown on the right hand side of Fig. 3.2. 

A data acquisition system was attached to the control panel of the extruder in parallel with the existing controllers. Barrel temperatures, discharge pressure, motor current, and several downstream sensors were recorded at a frequency of once per second. The sensors downstream from the extruder were showing that the downstream part of the process was not contributing a significant level of variation to the profile dimensions. The rate was measured at 53 kg/h for a screw speed of... 

Figure 295. Single-mode, mechanical, variable-speed feeder drive control system with roll drive motor amperage sensor...

For each parameter, the pH, DO (dissolved oxygen), ORP (oxidation-reduction potential), temperature, agitation speed, culture volume and pressure can be measured with sensors located in the fermenter. The output of the individual sensors is accepted by the computer for the on-line, continuous and real-time data analysis. Information stored in the computer control system then regulates the gas flow valves and the motors to the feed pumps. A model of a computer control system is shown in Fig. 11. The computer control systems, like the batch systems for mammalian cell culture, seem to level out at a maximum cell density of 10 cells/ml. It may be impossible for the batch culture method to solve the several limiting factors (Table 10) that set into high density culture where the levels are less than 10 cells/ml. 

Use a low cost, no sensor required, variable speed motor-controller topology design. 

Rotation Speed. Most often, FSW and its variants use motors with internal control through drives. The motor speed is almost always controlled and is often monitored via output from motor drives. Separate sensors are not required. 

In some systems the rotation of the crystal and the detector is mechanically coupled with gears. Other systems have no mechanical coupling but use computer-controlled stepper motors for the crystal and the detector. The newest systems use optical position control by optical sensors or optical encoding devices. Optical position control permits very high angular precision and accuracy and very fast scanning speeds. 

One method of feeding material into an entry loop is by simply driving the payoff mandrel with an electric motor (see Fig. 11). Normally, this is accomplished with a DC motor, but on slow speed lines, an AC motor with an on-off -type operation may be adequate. When a DC motor is utilized, the loop position is usually automatically controlled with a set of photocells and flood lights or an ultrasonic sensor. This method of paying off material from the master coil is quite acceptable provided there are no stickers from the annealing furnace or any dents or damage to the sides of the coil. These defects would cause the material to stick to itself and not pay off with the force of gravity as it is uncoiled. 

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